Method and apparatus for producing thick sheets from fibrous pulp



July 28, 1925.

O. J. SALISBURY METHOD AND APPARATUS FOR PRODUCING THICK SHEETS FROM FIBROUS PULP Filed Nov. 6. 19 3 Sheets-Sheet 1 xfi 01 10 1453 Hvu h An mi k-2 141 21. 5. 1 17 3. 1) r July 28, 1925.

o. J. SALISBURY METHOD AND APPARATUS FOR PRODUCING THICK SHEETS FROM FIBROUS PULP Filed Nov. 6. 1922 3 Sheets-Sheet 2 III VE/I/ TOR I 0| I I 1 I QI l M, what w In A TTOR/VE VS July 28, 1925. 1,547,613

o.- J. SALISBURY METHOD AND APPARATUS FOR PRODUCING THICK SHEETS PROM FIBROUS PULP Filed Nov. 6. 2 3 Sheets$heet 5 ATTORNEYS Patented July 28, 1925.

UNITED STATES 1,547,613 PATENT I OFFICE.

ORANGE J. SALISBURY, OF SALT LAKE CITY, UTAH.

METHOD AND APPARATUS FOR PBODUOIN G THICK SHEETS FROM IIBBOUS PULP.

Application filed November 8, 192?. Serial No. 599,253.

To all whom it may concern: I

Be it known that I, ORANGE J. SALISBURY, a citizen of the United States, residing in Salt Lake City and State of Utah, have invented certain new and useful Improve.- ments in Method and Apparatus for Producing Thick Sheets from Fibrous Pulp, 0f which the following is a specification.

This invention relates to the manufacture of sheets of substantial thickness from fibrous pulp.

The object of this invention is to provide a method and apparatus which Wlll. continuously produce a complete product from the fibrous pulp and which will automatrcally subject the raw material to the required steps in the proper sequenceand for the required lengths of time without manual control and with machine elements of the simplest construction, which will effect the production of -a superior material because of the continuous predetermined sequence and duration of the various steps of manufacture and the continuous support afforded to the material from the initlal step to the final discharge.

A' further object of this invention is to produce an improved material at a faster rate and at less expenditure of labor, material and money, than it has been possible to accomplish with the methods heretofore employed. y

,Methods which have heretofore been employed to manufacture such sheets from pulp have consisted of various steps independently performed, necessitating trans-' porting the material at least once, and usually several times before it' is com lete.

During this movement from .one point to' another, the material was often cracked or broken, and it was most difficult to maintain the material in such a state that it was ready for the next operation. Materalsof this sort require that the bonding of fibers which is accomplished in the first step of manufacture should remain undisturbed until the material is completely'finished. The bonding has no appreciable strength until the material is completely finished and any strains placed upon it by mechanical or thermal action invariably results in a weakened and inferior product. These troubles magnified -rapidly as the thickness of the manufactured sheet increased.

The process and apparatus disclosed herein are especially adapted to avoid subjecting the material to any strains until it is discharged completely. At no point is thematerial left unsupported or itssupport disturbed, the steps following in continuous sequence. There is no delay'between steps and therefore no difliculties due to changes between such steps, the heating and drying methods employed are adapted to produce the most rapid results while so modifying the final stages that no thermal strains or cracking due to heat can happen. Due to" the improvements which this invention provides, it is possible to manufacture sheets of a thickness before impossible.

Like num erals refer to'like parts throughout the several views of the drawing which the device removed to more clearly illustrate the relationof the various parts; I

F1gure 3 is a detail of apart of the devlce.

Figure f is a fragmentary view of another part of the device.

5, of the detail shown in Figure 4.

Figure 6 is a sectional viewon line 6 of ure 1 a screen belt 20 is driven in the direc- I tion of the arrow around the drum 30 through the pulp tank 40 under the concentrated rapid heating element 50 then through the modified finish drying chamber 60; around the tension roller 27 and through the cleaning device back to the drum 30.

The screen belt 20 is constructed of such Figure 5 is a sectional view taken on line material as canvas, asbestos, or, fine wire cloth of such consistency that liquid will easily pass "through, while fibersand solid material will be retained on its surface- The detail of the construction of thisbelt 20 is best seen from Figures 4, 5 and -6. Figure l which the screen material 21 is supported by the reinforced edges 22 shown in section in Figure 5 and by the crosspieces 24 shown in section in Figure 6.

The reinforced edges 22 are provided with sprocket holes 23 which engage sprocket teeth 38 on the drum 30 and form the driving means for the belt 20. A modified form of screen belt used for the manufacture of a corrugated sheet product (see Fig. 10) is shown in Fig. 7 the screen materlal 21 is herecorrugated to the form of the pro osed product and the modified drum 30 (Fig. 9) which is used with this belt is also provided with corrugations 32? into which the belt corrugations fit. i

This belt 20 travels the full length of the chamber 60 and is tensioned and supported at its discharge end by the tension roller 27, which is provided with adjusting devices 28 for taking up any slack in belt 20. At intermediate points in the' belt travel rollers 29 are provided to support the belt and prevent its sagging when loaded. From roller 27 the belt returns to the drum 30 preferably through a cleaning means such as the brushes 80 which remove any material liable to clog the openings in the belt material, and so prepare it for re-use.

The drum 30 (see Fig. 8) is divided into several tight compartments 31 which are isolated from each other and faced at the periphery of the drum with porous material 32. Each of these compartments 31 is provided with a port 34 (dotted lines) and over these ports a stationary valve 35 is arranged to connect the compartments 31 which are submerged in the pulp solution to a suction conduit 36.

The drum 30 is supported over, and

dipping into, a pulp tank 40 and is rotated,

through any suitab form of drive, from a power source (not shown). As this drum 3O revolves it drives through its sprocket teeth 38 the screen belt 20, as previously described.

The pulp tank 40,- preferably of the semicircular form shown, is supported by such means as the legs 41 and has a pulp solution inlet 42. It is customary to mix the fiber pulp into solution with a suitable liquid,

. which may be of such nature as to aid in forming a bond between the fibers when dried, and then introduce it through the inlet 42 to the tank 40. .To prevent the pulp settling out of solution it is'preferable to provide an agitating means 43 to kee the pulp thoroughly mixed with the liqui The concentrated rapid heating element 50 comprises a combustion chamber which conforms to the shape of the drum 30 and is only slightly removed therefrom at the surface 51. A gas, or oil, burner 52 keeps this combustion chamber very hot at the surface 51 and this hot surface is in such close relationship to the belt 20 that any thing attached thereto is rapidly heated and dried. Any heat from element 50 which is not directly applied to the belt 20 as it passes around drum 30, assists in raising the temperature of the modified finish drying chamber 60. This drying chamber 60 is further provided with heating elements filarranged above and below the belt 20, and with air circulating ports 63 which communicate with the air ducts 64 leading to a fan 65 to circulate hot air and to carry away moisture as the heat evaporates it.

In operation the fiber pulp, in solution in any suitable liquid, is supplied through inlet 42 to the pulp tank 40. The drum 3U revolves slowly driving the belt 20. The drum compartments 31 at the lower part of drum 30 are placed in communication with the suction conduit 36 by the ports 34 and the valve 35 drawing the liquid of the pulp solution through the belt material 21, through the porous cylinder surface 32, through a compartment 31, through the valve 35 and out through conduit 36. This deposits the fiber pulp on the screen belt 20 in an even layer and as the drum and belt move this layer of pulp is carried upward out of the solution and under the rapid heating means 50 which vaporizes a large portion of the moisture still held inthe pulp layer. The still damp pulp layer then assumes a horizontal plane as the belt 20 leaves the drum 30. Since the pulp layer is not completely dry and is supported at every point by the belt 20 the pulp layer also straightens and flattens without cracking and without straining or injuring the bonding between the fibers. The flat pulp layer, or sheet, is now carried along over and under heating elements 61 while the air currents circulated by fan 65 hastens the drying by carrying away the vaporized moisture. This part of the drying is carried on at a far slower rate than that employed 0pposite heat-ing element 50, for now that the pulp sheet is more nearly dry too rapid heating will dry the sheet surface hard and then vaporize the moisture in the center of the sheet until the vapor pressure rises to a point which disrupts the hard sheet surface causing cracks and fissures which can not be tolerated in a salable product. This has been the great difiiculty when it was attempted to manufacture sheets of considerable thickness, and previous to this invention it has not been possible to turn out a first class thick product. The travelling belt 20, the speed of which. may be controlled by changing the speed of drum 30, permits of a predetermined drying rate and of a predetermined proportion between the evaporation occurring before straightening and that occurring after the straightening of the'sheets. Thus for a given thickness of. product desired a rate of manufacture may be determined and setting the machine at that rate will cause the submersion of the belt 20 for a long enough time to attain a deposited layer of pulp of the required thickness and will cause this deposited layer to be subjected to the action of the various drying means for the length of time necessary toefl'ect proper drying without damage.

Thus increasing the belt speed will decrease the length of pulp depositing time, decrease the thickness of the pulp layer, decrease the time under the drying means and the time in the finish drying chamber, the product turned out will be uniform in thickness and dried to the required degree.

On the other hand, decreasing the belt speed will increase the length of pulp depositing time, increase the thickness of the pulp layer, increase proportionately the time in passing both heating zones and produce a product which will be exactly the same degree of dryness and uniformly simllar in construction, except for greater thickness, tothe sheet produced by the increase speed previously considered.

It will be seen then, that by the snnple changing of speed a product of any desired thickness may be obtained and that such a change of speed will automatically change,

in the proper ratio, all of the various steps incidental to the production of a finished product. Itwill also be seen that the pulp sheet is supported from the tlme of lts first formation to the time of itsdischarge to the apron 69 leading to a double set of rubber rolls 7 0 which put the final finished surface on the completed sheet product.

It will be evident that while for purposes of illustration the various parts of the device have been shown for the production of fiat sheets, that any, or all, the parts may be so modified as to produce a product having corrugations running laterally or transversely of the sheets, as is indicated in Figures 7 and 9, or modified to produce a curved sheet, a sheet having a depression, or multiple depressions, if such are desired, for such purposes as wall paneling in house construction. It will also be evident that the order or intensity of the various steps may be modified,-,and that many other modifications may be made without departing from the spirit of the invention or the scope of the following claims.

What I claim is: i

1. In apparatus for the continuous manufacture of board from fibre pulp, the combination of a screen belt, recipitating means, rapid drying means, iii'iish drying means, said drying means being adapted to dry the board without further'compacting the same, and without contacting therewith,

a belt cleaning means and a driving means.

board comprising a screen belt, in combination with a filter drum provided with suction means, a direct heater, an indirect heater, neither of which contacts with the material to be dried, an air circulating means and finish rolls.

4. An apparatus for the manufacture of board comprising in combination a screen belt, a suction" filter drum, a concentrated rapid first drying means, a slower finish drying means distributed over a greater space and spaced from the board, air circulating means and finish rolls.

5. In apparatus for the manufacture of board from fibre pulp, the combination of a continuous moving screen belt, means for submerging the belt at one portion of its travel in a pulp solution to precipitate the fibre pulp thereon, means for applying con centrated heat adjacent to the submerged portion to rapidly dry the larger portion of the entrained moisture, means for straightening the screen belt and the partially dried pulp, means for gradually completing the drying of the board while supported by the belt in a horizontal plane and pressure applying means for finishing the surface of the discharged board.

6. The method of'manufacturing board from fibrous pulp which comprises forming the pulp upon a belt by suction, then applying heat to rapidly remove a large part of the moisture content, then straightening the belt and the pulp thereon in a horizontal plane and simultaneously completing the drying of the pulp, and finally passing the dried board'through rolls to finish its surfaces.

7. The method of manufacturing board from fibrous pulp which comprises continuously forming the board by suction from fibre pulp in solution, then applying heat and suction to draw ofi' entrained moisture, then carrying the shpported partly dry board between heaters arranged above and below its path of travel and circulating air to complete the drying of the board, and finally passing the dried board between rollers to finish its surface. I i

8. The method of continuously manufacturing board from .fibre pulp, which comprises rapidly filtering pulp from a solution to form the board, then applying concentrated heat to. rapidly dry the larger portion of the moisture from the board, then straighteningthe board, then drying out Ill the remaining moisture at a slower rate, and finally passing the board between rolls to finish its surface.

9. The method of manufacturing thick sheets from fibrous pulp which consists in first introducing a continuous porous belt into a solution of pulp to form a coating thereon, second remove the belt and its coating from the solution to non-compacting drying means while the coating is still supported on the belt to a point of discharge where it is acted upon by flattening and straightening rolls.

10. The combination with a travelling screen belt for the continuous manufacture of building material from fibre pulp, a suction pulp precipitating means. a rapid heat drying means, a modified-finish heat drying means both of said heat drying means spaced from said belt and a belt cleanin means.

11. In the continuous manu acture of board from filter pulp the combination of a moving screen belt, adapted to move through a pulp solution, a rapid drying means adjacent the belt near its exit from the pulp solution but spaced therefrom, and a relatively slow drying means remote from the pulp solution, and spaced from said belt said screen belt adapted to pass under the rapid drying means, and throughthe slow drying means, discharge its burden and return to the pulp solution.

In testimony whereof I have affixed my signature to this specification.

ORANGE J. SALISBURY 

